1. Field of the Invention
The invention relates to devices [according to the preamble of claim 1] for subsequently installing a fluid meter in a pipeline which is under pressure.
2. Description of the Related Art
From EP-A 344 777, DE-C 36 27 393 or DE-A 32 42 763 devices are known with which a fluid meter, for example, a water meter, can be retrofitted in a pipeline. A precondition for this is that a T-piece of a shut-off valve is already present in the pipeline. After unscrewing the valve hand, a branch fitting is screwed onto the T-piece on whose upper side the fluid meter is seated. In the interior of the branch fitting an insert is provided which guides the fluid out of the pipeline and, after it has passed through the fluid meter, returns it into the pipeline.
The precondition for the use of these so-called valve meters is that in the pipeline there is already a T-piece of a shut-off valve. In the case that such a shut-off valve is not present, the subsequent installation of a fluid meter is only possible with elaborate stamping, cutting, welding and soldering work. In both cases the fluid line must be shut off and emptied. This is unsatisfactory.
The present invention has therefore the object to provide a device of the aforementioned kind which makes it possible to retrofit fluid meters even when no T-piece is present and the fluid line is under pressure.
This object is solved by a device for retrofitting a fluid meter into a pipeline that is under pressure includes a branch fitting with a branch socket, a flow-guiding insert for guiding the fluid out of the pipeline into the fluid meter and for returning the fluid into the pipeline, and a branch socket with an inner thread corresponding to a thread on the fluid meter. The branch fitting has two ceiling sockets which can be placed on the pipeline in a fluid type manner and which are longitudinally divided along the pipeline. The branch socket has an outer thread, wherein a lock fitting can be tightly screwed onto the outer thread. The lock fitting is composed of a cylinder socket and a shut-off device with a ball valve having an opening mounted in the cylinder socket. The lock fitting further has a removable lid with a guide socket and a rotatable actuation rod extending through the guide socket and being liftable and lowerable through the opening of the ball valve when the ball valve is in an open position. The actuation rod can be selectively connected to a milling head for drilling into and drilling through the pipeline, or a securing device for holding the fluid meter during its mounting or demounting.
Tapping stop valves with whose aid connecting locations can be retrofitted in pressurized gas and water lines have been known for more than 100 years. Compare, for example, U.S. Pat. No. 463,524, DE-U 93 16 819, DE-U 74 10 858, DE-A 25 15 235 or GB 13 67 074. All of these tapping stop valves have adjacent to the drilled pipeline a shut-off element. According to U.S. Pat. No. 463,524, this is a parallel slide gate valve, while in the newer documents generally a ball valve is provided. Despite certain similarities between the device according to the invention and the tapping stop valves of the prior art, the known tapping stop valves are not suitable for the use according to the invention.
The invention makes it possible to retrofit any fluid line, independent of whether it is buried or freely accessible, with a fluid meter without having to shut off the fluid line and empty it.
A further advantage of the device according to the invention is that it can be used also to exchange the fluid meter after expiration of the legal calibration period, also without having to shut off the pipeline and empty it.
According to one embodiment of the invention the material of the branch fitting is matched to that of the pipeline. With this measure it is possible to prevent stress corrosion. The main reason for this measure is, however, the electrical connection between pipeline and fitting required in a predominant number of cases.
According to a preferred embodiment of the invention, the diameter of the branch socket and of the milling head are greater than the diameter of the pipeline. In this way, the pipeline is completely separated and the insert for separating the flows seals relative to the branch fitting, not relative to the pipeline. In this way, the sealing surfaces can be matched optimally relative to one another.
Advantageously, the branch socket has an extension below the pipeline. This is also provided primarily to make possible the complete separation of the pipeline without the risk of damaging the branch fitting.
It is understood that the flow-guiding insert, with whose aid the fluid can be guided out of the pipeline and, after it has flown through the fluid meter, can be returned into the pipeline, is of especially great importance. This insert must ensure, for example, that no bypass flow bypassing the fluid meter can occur.
According to a first embodiment, this concerns a cylinder with an inner partition. The cylinder and partition form an inflow channel with an inlet opening aligned with the pipeline and an outflow channel with an outlet opening aligned with the pipeline. In this connection, the fluid meter can be seal-tightly positioned on the cylinder.
The cylinder and partition can be advantageously comprised of two parts insertable into one another.
According to an alternative embodiment, the flow-guiding insert has a partition and a sealing plate which is connected to the partition and closes off the branch socket, wherein the sealing plate can be inserted in the branch socket and, optionally, its extension in a fluid-tight manner. The sealing plate is open at the inflow side. At the outflow side it has a central opening which corresponds to the outlet of the fluid meter. This insert requires only minimal space so that the cross-section available for fluid flow is correspondingly large.
Preferably, the insert is sealed by means of a profiled packing in the branch socket. This profile packing comprises approximately a U-shape. U-shaped profile packings are, for example, widely used in parallel side gate shut-off valves.
According to an advantageous embodiment, the inner wall of the branch socket has guide grooves or guide strips for the partition. In this way, pressure pulses in the pipeline cannot change the position of the partition.
According to a further embodiment of the invention, a nonreturn valve is integrated into the insert, preferably directly behind the outlet of the fluid meter.
Should it be desired to measure the temperature of the fluid, a temperature sensor can be inserted into a prepared bore of the branch socket.
Should it be desired to shut off the fluid flow, a shut-off valve can be inserted at the inflow side and/or the outflow side of the branch socket. This makes it possible to exchange the fluid meter without having to use the lock fitting.
An especially simple arrangements results when the shut-off valve is an inflatable bladder. This shut-off bladder is inflated by means of a pressure pump. Emptying of the shut-off bladder is realized by the inner pressure of the pipeline.
Should it be desired to arrange a shut-off valve outside of the branch socket, it can be integrated into the sealing socket(s). For this purpose, at least one valve socket is provided in addition to the branch socket onto which the lock fitting with the milling device for drilling into and drilling through the pipeline or a valve lid can be positioned. In this connection, the valve lid has an opening for valve actuation. Construction and operation correspond to what has been explained in relation to the branch socket.
According to a first embodiment of the invention, a cylindrical plug is rotatably and seal-tightly inserted into the valve socket.
An alternative embodiment suggests a plunger valve with plunger.
The longitudinally divided sealing sockets of the branch fitting can be closed by conventional means, for example, by screws and nuts and also with clamping straps.
In order to prevent that metal shavings can be entrained by the fluid flow when drilling into the pipeline, a permanent magnet can be arranged at the milling head.